SGA infants are at risk for poor postnatal growth and this is especially true in infants who have symmetrical intratuterine growth retardation (SYM; wt, ht & ofc <10th%ile) versus infants with asymmetrical growth retardation (ASYM; wt<10th%ile; ht & ofc 10-90th%ile). SYM indicates growth retardation that begins to occur early in pregnancy, while ASYM more often represents growth retardation that occurs in late pregnancy. It is unknown how SYM vs ASYM growth retardation effects postnatal growth in preterm, ELBW infants.

Postnatal growth and nutrition support was examined in 47 ELBW admitted for>7 days to the NICU at University Hospital, Salt Lake City, UT. Growth parameters were compared to gestational age using growth charts adapted from Lubchenco with the 10th%ile for 23 and 24 wks were estimated by extending the slope of the 10th%ile grid line. Thirty-four SYM and 13 ASYM infants were identified. No differences were found between gender or ethnic distribution, or the initiation or use of parenteral nutrition support. SYM infants had greater gestational age and birth weight than ASYM infants (29.6±1.9 vs 26.9±1.9 wks; 786±151 vs 572±128 gms, both p<0.001). Feeding intolerance (residuals, distension,and/or abnormal stools)resulting in delay of enteral feedings for > 24 hours occurred more often in ASYM infants (77% vs 41%; p<0.05) and delayed the establishment of enteral nutrition (27.5±14.7 vs 14.8±5.8 days;p<0.001). Average daily intake and weight gain did not differ between groups. Time to achieve 2.0 kg body weight was significantly longer for ASYM infants (92.6±21.8 vs 72.4±12.1; p=0.05), however, we attribute this finding and the increased feeding intolerance to the ASYM infants' lower gestational age and birth weight.

We conclude that preterm ELBW infants with symmetrical growth retardation do not experience slower postnatal growth than preterm ELBW infants with asymmetrical growth retardation.We speculate that: 1) at <28 wks gestation, the majority of SYM infants are normal, but constitutionally small and 2)preterm ELBW infants with ASYM growth retardation, if left in-utero, would continue to experience growth insult resulting in symmetrical deficits.